Ok, just checked this morning, sorry I have a bad memory. It is 0.069 cubic feet so around 2 liters 🙂
2 liters v/s 3.4 liters now that makes sense and corelates with the differences I get.
q: without measuring tools how do we build anything? the published specs dont seem worth trusting.
q: if published specs are not to be trusted how do yo what drivers even to buy? is a SS woofer really better than a Vifa?
q: without measuring tools how do we build anything? the published specs dont seem worth trusting.
q: if published specs are not to be trusted how do yo what drivers even to buy? is a SS woofer really better than a Vifa?
Yes exactly. No one can pretend building a good quality loudspeaker without measuring. Putting drivers in a box according to the manufacturer spec as well as using the nominal impedence to build the crossover are very inaccurate.navin said:
Mostly based on pass experience, people advice on this forum and a bit manufacturer quality process (some of them publish accurate specs).
Thiele-Small test
Navin, Ashok and Palesha,
I think you have gone through the thread I started on TS test in this forum. As your compatrior there is a question I would like to ask you all urgently -- what measurement tools do you use? Specifically, what AC Voltmeter do you use? How dedicated is it? How expensive?
You have mentioned some of those speakers that I only get to see in ads. Are they available in India? Could you get me the address?
Thanks.
Navin, Ashok and Palesha,
I think you have gone through the thread I started on TS test in this forum. As your compatrior there is a question I would like to ask you all urgently -- what measurement tools do you use? Specifically, what AC Voltmeter do you use? How dedicated is it? How expensive?
You have mentioned some of those speakers that I only get to see in ads. Are they available in India? Could you get me the address?
Thanks.
i used leap / lms untill the friend who had it moved. now i have sourced another person who has leap/lms but since i dont know him too well and he is suspicious of diyers i have to send my driver to him via another source.
leap/lms is dongle protected so yo have to buy your own copy.
all the drivers i have have been imported by me legally. i normally import from the US. in the past i imported fro A&S (now defunct) and Audio Concepts (only their 12" woofers). Now you can get them from singapore too. Drivers are OGL oyu only have to pay duty and customs (cvd etc..and octroi in bombay). i work it at Rs. 80 per USD for ease of budgeting.
remember to get a speical packing as drivers are fragile and can get damaged. other friends i know hand carry the mid and tweeters and import the woofers for their purpose.
CMM used the be the dealer for Focal and Morel. They flopped at that.
Novaudio i think is still the oficial distributor of SS and Vifai and I would guess all of dst but the best source is thailland and china (ss has a operation there). i got my vifa tc spekaers form thailand.
i have wondered if it made sense to build high end speakers in India. The operational infrastructure is all there, distribution is a still limited (onyl big metros can be covered) but would it be worth the time? I find the market too small. by high end I mean a good 5" or 6" 2 way retailing at s. 20,000. a good 2 x 6" or 3 x 6" tower retailing at Rs. 50,000.
leap/lms is dongle protected so yo have to buy your own copy.
all the drivers i have have been imported by me legally. i normally import from the US. in the past i imported fro A&S (now defunct) and Audio Concepts (only their 12" woofers). Now you can get them from singapore too. Drivers are OGL oyu only have to pay duty and customs (cvd etc..and octroi in bombay). i work it at Rs. 80 per USD for ease of budgeting.
remember to get a speical packing as drivers are fragile and can get damaged. other friends i know hand carry the mid and tweeters and import the woofers for their purpose.
CMM used the be the dealer for Focal and Morel. They flopped at that.
Novaudio i think is still the oficial distributor of SS and Vifai and I would guess all of dst but the best source is thailland and china (ss has a operation there). i got my vifa tc spekaers form thailand.
i have wondered if it made sense to build high end speakers in India. The operational infrastructure is all there, distribution is a still limited (onyl big metros can be covered) but would it be worth the time? I find the market too small. by high end I mean a good 5" or 6" 2 way retailing at s. 20,000. a good 2 x 6" or 3 x 6" tower retailing at Rs. 50,000.
The difference between the published specs and the measured specs on that Peerless 850102 are is nearly so gruesome as it appears.
Parameters interact with each other. If Speaker A has an Fs 40% higher than speaker B, but it also has a Vas half as much, then the two speakers are approximately equivalent. The parameters can shift around quite a lot, but yo can end up in the same place.
I would like to see those parameters more accurate, but take a look at what happens when you put the Peerless in a 2 liter closed box.
The box built according to published specs is in red
The box built according to measured specs is in blue
As you can see here, though the specs vary widely from what is published, the speaker will perform very nearly to specs when placed in a box.
I have used Peerless drivers before myself, and found this to be true. The specs seem to vary from published, (though not this far, from my experience) but the speaker performs pretty much right on the money when placed in a box.
Parameters interact with each other. If Speaker A has an Fs 40% higher than speaker B, but it also has a Vas half as much, then the two speakers are approximately equivalent. The parameters can shift around quite a lot, but yo can end up in the same place.
I would like to see those parameters more accurate, but take a look at what happens when you put the Peerless in a 2 liter closed box.
The box built according to published specs is in red
The box built according to measured specs is in blue
As you can see here, though the specs vary widely from what is published, the speaker will perform very nearly to specs when placed in a box.
I have used Peerless drivers before myself, and found this to be true. The specs seem to vary from published, (though not this far, from my experience) but the speaker performs pretty much right on the money when placed in a box.
Attachments
According to WinISD, the Qtc of the published specs is 0.71. For the measured specs it is 0.74.
Where the box built according to published specs is 3 dB down, the box built according to measured specs is 4.3 dB down.
This is certainly acceptable performance. Of course, it is not unfair to ask for the published and measured specs to be considerably closer.
Still, like the saying goes, all's well that ends well. 🙂
Where the box built according to published specs is 3 dB down, the box built according to measured specs is 4.3 dB down.
This is certainly acceptable performance. Of course, it is not unfair to ask for the published and measured specs to be considerably closer.
Still, like the saying goes, all's well that ends well. 🙂
Dear r.s. dhar,
I am using softwares to measure T/S parameters. I have woofer tester from USA and DAAS 32 from Germany. I crosscheck the measurement but there is always difference of 5~7% in Vas and Fs. They are tested under perfectly same conditions, same place, same time with same weight. Thsi is quite fast but a costly affair for people in India.
Mahendra Palesha
I am using softwares to measure T/S parameters. I have woofer tester from USA and DAAS 32 from Germany. I crosscheck the measurement but there is always difference of 5~7% in Vas and Fs. They are tested under perfectly same conditions, same place, same time with same weight. Thsi is quite fast but a costly affair for people in India.
Mahendra Palesha
I agree with you guys. In fact, even if the measured parameters are very different, it does not make a big difference on paper and smart the guy will be if he can see the difference with listening test. In my case, both drivers were very close to be matched.
My box is built based on measured parameters and I am still impressed how these drivers can go low for the size.
My box is built based on measured parameters and I am still impressed how these drivers can go low for the size.
Hi,
Before doing any measurement on new speakers it is always wise to run them in for long enough time. I usually do it for 48 hours connected at a sine generator set to fs. Fs can drop more than 5% after running in.
Oh and NEVER use the added weight method for speakers with aluminium cones. You will for sure damage the very thin cone. Own experience
For plastic (PP/TPX/Kevlar) cones it can be done with two sided adhesive tape. For the weight you can use several kinds of steel plate like washers or key holding rings. But be very careful not to damage the speaker.
For a low-cost DIY microphone have a look at:
http://www.linkwitzlab.com/sys_test.htm#Mic
Monacor with part number MC2000 also sells the same Panasonic capsules. I am using this homebrew one without calibration and I have found it accurate enough for DIY.
Before doing any measurement on new speakers it is always wise to run them in for long enough time. I usually do it for 48 hours connected at a sine generator set to fs. Fs can drop more than 5% after running in.
Oh and NEVER use the added weight method for speakers with aluminium cones. You will for sure damage the very thin cone. Own experience
For plastic (PP/TPX/Kevlar) cones it can be done with two sided adhesive tape. For the weight you can use several kinds of steel plate like washers or key holding rings. But be very careful not to damage the speaker.For a low-cost DIY microphone have a look at:
http://www.linkwitzlab.com/sys_test.htm#Mic
Monacor with part number MC2000 also sells the same Panasonic capsules. I am using this homebrew one without calibration and I have found it accurate enough for DIY.
palesha, can you pleae ofer details of your equipment? if your results are onyl 5-7% off you got a very good soruce of drivers. i find my results more than 10% off from published specs, usually 15-40% off.
Pjotr, use blu tak it is easier than double sided tape. i put the weight on the dust cap not on the cone. so far i have not got any alumin. drivers but i will heed your warnng nonetheless.
Pjotr, use blu tak it is easier than double sided tape. i put the weight on the dust cap not on the cone. so far i have not got any alumin. drivers but i will heed your warnng nonetheless.
Dear Navin,
The difference of 5~7 % is between the two testing systems. This is about testing same speaker on both systems with similar testing conditions. Regarding DAAS32 is like lms or any other speaker testing software with proprietory PC card. It is from Germany. If u want let me know because my friend is their agent right here in Pune. Woofer tester is another woofer testing box with PC software sold by parts express.
Mahendra Palesha
The difference of 5~7 % is between the two testing systems. This is about testing same speaker on both systems with similar testing conditions. Regarding DAAS32 is like lms or any other speaker testing software with proprietory PC card. It is from Germany. If u want let me know because my friend is their agent right here in Pune. Woofer tester is another woofer testing box with PC software sold by parts express.
Mahendra Palesha
Hi navin,
I have found bluetack or similar stuff can leave a residue that can be difficult to remove. Double-sided adhesive tapes come in various flavours, ones with strong adhesives and ones with weak adhesives. I am using of course those with weak adhesive. For speakers with a phase plug I used large key-holding rings. I did cut 3 strokes of 5 mm from ds tape and putted that on the ring so there are 3 little handles of tape left to remove the ring afterwards. That worked pretty well.
But now I stick to the volume method. Tip: For a nice volume of air: Look for a terracotta flowerpot! There are many sizes available. Measuring volume is easy: Simply fill it with water (after you closed the little hole in the back of course). I am also using terracotta flowerpots for the mid-speaker compartment in my boxes. Stand-alone they will ring like a bell, but properly mounted they are acoustically very dead. 😉
For speaker testing with your soundcard also have a look at http://www.purebits.com/
For T-S parameter extraction it uses a MLS signal. I have found that this seems less accurate than doing it by hand with a sinus generator. Can’t figure out why. But nonetheless it is accurate enough.
I have found bluetack or similar stuff can leave a residue that can be difficult to remove. Double-sided adhesive tapes come in various flavours, ones with strong adhesives and ones with weak adhesives. I am using of course those with weak adhesive. For speakers with a phase plug I used large key-holding rings. I did cut 3 strokes of 5 mm from ds tape and putted that on the ring so there are 3 little handles of tape left to remove the ring afterwards. That worked pretty well.
But now I stick to the volume method. Tip: For a nice volume of air: Look for a terracotta flowerpot! There are many sizes available. Measuring volume is easy: Simply fill it with water (after you closed the little hole in the back of course). I am also using terracotta flowerpots for the mid-speaker compartment in my boxes. Stand-alone they will ring like a bell, but properly mounted they are acoustically very dead. 😉
For speaker testing with your soundcard also have a look at http://www.purebits.com/
For T-S parameter extraction it uses a MLS signal. I have found that this seems less accurate than doing it by hand with a sinus generator. Can’t figure out why. But nonetheless it is accurate enough.
Pjotr said:
Yes this is true but even if there is a small error inserted by the test setup/software/room/etc, the subjective difference will be not notable.
anyone here use MLSSA? might get a look see soon.
palesha,
I am a DIY. I build about 1 pair of speakers every few years.
currently I am working on a 2 way using a Vifa TC series midbass and tweeter. there will also be a center channel using 4 shielded Vifa TC series woofers and 2 3/4" sheilded TC series tweeters.
I dont have any speakers for the rear yet. I might use an older pair of Boston Acoustics A40 or JBL Pro III for now.
for a sub i was thinking of using your 12" active sub but it did not mate well so i found 2 8"Eminence woofers and am now building a sub amp using 7294 chip. initial trials wihtout the amp sounded good.
I also have a shielded pair of Vifa 6" woofers and shielded 1" tweeters that i am holding on to for a shielded 2 way system that i might need later. actually the only speaker that need to be shielded are the center channel. I guess I will make 2 center channels and see which is better. 1 with 4 4" woofers and 1 with 2 6" woofers.
once in a big while I find some nice drviers and build a system around this. hence i cant really afford to buy a measuring system. these drivers cost me about rs. 700 each (about euro 14 each) in bombay (mumbai).
palesha,
I am a DIY. I build about 1 pair of speakers every few years.
currently I am working on a 2 way using a Vifa TC series midbass and tweeter. there will also be a center channel using 4 shielded Vifa TC series woofers and 2 3/4" sheilded TC series tweeters.
I dont have any speakers for the rear yet. I might use an older pair of Boston Acoustics A40 or JBL Pro III for now.
for a sub i was thinking of using your 12" active sub but it did not mate well so i found 2 8"Eminence woofers and am now building a sub amp using 7294 chip. initial trials wihtout the amp sounded good.
I also have a shielded pair of Vifa 6" woofers and shielded 1" tweeters that i am holding on to for a shielded 2 way system that i might need later. actually the only speaker that need to be shielded are the center channel. I guess I will make 2 center channels and see which is better. 1 with 4 4" woofers and 1 with 2 6" woofers.
once in a big while I find some nice drviers and build a system around this. hence i cant really afford to buy a measuring system. these drivers cost me about rs. 700 each (about euro 14 each) in bombay (mumbai).
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